Project Summary: This proposal utilizes genetic tools that manipulate components of sphingolipid/sterol rich liquid-ordered microdomains. Lipid microdomains in neurons localize exocytic machinery required for neurotransmission and localize and modulate ion and neurotransmitter channels. Lipids that form these microdomains are also mechanistically linked to a growing number of neurodegenerative diseases including, sphingolipid storage diseases, Alzheimer's Disease, and Huntington's Disease. These same lipid species are also intimately linked to membrane trafficking of neurotransmittor containing vesicles in neurons. The underlying hypothesis driving this proposal is that sphingolipid/sterol microdomains are required for membrane trafficking at the plasma membrane and disruption of these microdomains is an underlying cause of synaptic dysfunction and, ultimately, neurodegeneration. Utilizing the genetic model system of Drosophila, mutant lines that alter sterol and sphingolipid metabolism and transport will be assayed for neuronal lipid composition, trafficking and microdomain formation. Furthermore, these sterol/sphingolipid metabolism mutants will be assayed for synaptic function. Using genetic and pharmacalogical techniques, neurodegeneration due to disruption of lipid regulated activity in a range of neuron types will be assayed. Utilizing Drosophila will facilitate the rapid discovery of novel regulatory mechanisms of neuronal lipid microdomain organization and neuroprotective pathways. Relavance to public health: A growing number of human neurodegenerative diseases feature accumulation/mistrafficking of various lipid species or misregulation of lipid metabolism. These same lipids are important signaling molecules or regulators of the synaptic vesicle cycle essential for neurotransmission. The central role lipids execute in synaptic function and neurodegenerative diseases dictates the need to better understand neuronal membrane lipid composition as well as lipid trafficking/signaling in neurons.